Variable frequency vibrating device



July 1.7, 1951 LE ROY w. LlEscH VARIABLE FREQUENCY `vnam'mc: DEVICE mea'aune 111949 Patented July 17, 1951 OFFICE VARIABLE FREQUENCY VIBRATING DEVICE Le Roy W. Liesch, Chicago, Ill., assignor A.to

Chicago, Ill., a corpora- Velsicol Corporation,

non of Illinois Application June 11, i949, Serial No. 98,583

`Ii Claims.

This invention relates to improvements in adevice for vibrating an impact plate at a controlled frequency, said impact plate being adapted to hold a sample of discrete material of such character as to have its bulk density increased or its volume reduced by such vibration.

In the handling, packing and shipping of discrete material, especially in the dry state, it is desirable to know the extent to which the volume occupied by the material will change or its bulk density increase when the material is subject to vibration or impact forces.

This knowledge is particularly valuable -in the marketing of packaged discrete materials which between the time of packaging and the opening of the package for use the package may be roughly handled or may be subject to the vibration and vimpact forces incident to shipping.

The present invention comprises a simple, accurate and economically constructed device which can be employed to index a material with regard Ato lts characteristics of changing bulk density in response to vibration. impact or shock forces, the device being particularly characterized by its ilexibility as to the nature of the vibration, that is, the frequency of 'vibration which may be imparted to a sample of discrete material and the ease with which the device may be operated.

. Other objects and advantages of the present invention will be apparent from the accompanying drawing and following detailed description. ff The single figure comprising the drawing is a schematic wiring diagram of the electric1circuit employed, the physical structure of the impact "plate being shown diagrammatically.

'l Referring in detail to the drawing I0 indicates an electron tube of'the amplier-rectier type suchas a T-IIlLl tube. The tube Ill and the circuit associated therewith is energized from a source II of alternating current. The tube III carries eight terminals, numbered l to 8 respectively; terminals 2 and 'I comprising the filament or heater terminals; terminal 3 comprising the plate terminal; terminal 4 comprising the control grid terminal; terminals I and 6 comprising rectifier terminals and terminal comprising an auxiliary grid terminal.

It is to be understood that a conventional triode used in conjunction with a full or half wave rectifier tube may be substituted for the tube I0. However, the amplifier-rectifier tube of the type shown is preferred.

The filament or heater connected betweenterminals 2 and 1 provides energy for the discharge of electrons and is connected directly across the alternating current source II.

(Cl. S18-132) The platel circuit voltage is supplied from terminal I of the recti- Iier section of the tube, the current being filtered through a illter I2 comprising condensers I3 and resistance I4. From lter I2 lead I5 connects to auxiliary grid terminal 5 and through relay coll I6 to plate terminal 3. It can therefore be seen that variations in plate current will be effective to change the flux in core I1 around which coil I6 is wrapped. A relay switch I8 is activated by current passing through coil I6 to open ,the alternating current circuit from line I9 through a solenoid coil 20 to ,ground 2|, the opposite side of the alternating current line being grounded at 22.

. As will be hereinafter more fully described-a pulsating current is passed through the relay coil I6 which causes relay switch I8-to periodically open and close. The opening and closing of the switch I8 intermittentlyenergizes the solenoid coil 20. A core 23 is positioned within the sole-l noid coil 20 and as current periodically passes through coil 20 the core vibrates along its lon'- gitudinal axis. An impact plate 24 is positioned above the core 23 and as said core moves upwardly it impinges upon the lower surface of the plate 24, the rate of impacts upon the plate 24 being determined by the opening and closing of relay In utilizing my invention a beaker 25 may be positioned upon the impact plate 24, said beaker being provided with calibrations 26. Discrete material 2l may be positioned in the beaker 25 and plate 24 may be subjected to a series of impacts. As a result thereof the discrete material 21 wiil tend to settle in the beaker and the extent of settling for a given number of impacts per unit of time may be determined by the calibrations 26. Thus the characteristics of the discrete vmaterial 21 for a predetermined frequency of impact for a predetermined time may be ascertained. As has been hereinbefore described this information is particularly valuable wherein discrete material is packaged and the packages are subjected to relatively rough handling or where the packages may be transported over distances. Arr-index as to the degree of settlement may thus be obtained.

Inorder to automatically control the length of time that the plate 24is subjected to the impact forces a conventional timing mechanism 28 may be connected in series' with the solenoid coil 20 and ground 2|. The device 28 may be of conventional construction and'may be of the type which would automatically disconnect the circuit after rthe lapse of a predetermined period of time. f

In order to set up the desirable iluctuations y in current in the relay coil I6 an oscillator circuit 29 may be connected to the control gridcathode of the ampuner section or the tube m.`

its ,terminals until a predetermined voltage is applied across the terminals; Above .this critiimpressed across condenser 3l and tube 30. As has been hereinbeiore .described this E. M. F.

` is controlled by the variable resistance 36. Ac-

cal voltage the tube will function as a conductor a conductor of electricity.

Connected in parallel with tube 30 is a condenser Jl. One side of the tube 30 and a side of the condenser 3| are connected to ground 32. The opposite side of the tube 30 and condenser Il are connected through a condenser 33. a resistance 34 which in turn is connected by means of lead 35 to the lament or heater terminal 2 which is also grounded at 22. Terminal l of tube I0 is connected through variable resistance 36 by means of lead 31 to one side of the tube 30 and condenser 3|, that is, that side which is also connected to condenser 33. The upper portion oi' resistance 34 is connected by means of lead ll to terminal 4 of tube I0 which comprises the control grid terminal of the amplifier section of said tube. y

It will be noted that an E. M. F. is impressed across the tube 30 and condenser 3|, this E. M. F. being normally controlled bythe variable resistance I6. With the switch I! in thealternating current line closed an E. M. F. is established across condenser Il and tube 34. The current initially tends to charge the condenser Il. As the condenser is charging the E. M. I5'.y

-across the tube 30 is insulcient to cause said tube to act as a conductor. When the condenser 2| has been completely charged the E. M. F. across the tube Il will increase above the critical voltage of the tube 30 and as a consequence current will pass through the tube I0 and the condenser Il will discharge. During the period that the condenser 3| is charging current will also flow through the condenser 33 and resistance 34. A drop of potential will thereby be established between the control grid and the nlament or cathode of the tube. Current will then ilow from the cathode of the tube to the vplate of said tubeI and said current will also llowthrough thel relay coil I6 thereby opening switch Il and deenergizing solenoid coil 2l. After condenser 3| has been charged and tube ll becomes conducting the current which normally travelled through the resistance 34 is effectively short-circuited through the tube 30 and consequently the amplier section of tube l0 will be rendered inoperative, that is, no current will flow through the plate circuit thereof and hence switch Il will be closed. Current will flow in solenoid coil 20 until condenser 3i has been completely discharged and begins to charge. y In this fashion oscillatory current is set up in the grid circuit of the amplier section of tube Il, the amplified oscillations being effective to open and close relay switch il and energize and deenersolenoid coil 2l.

With a predetermined value of capacity for .of electricity. When the voltage is reduced be low said critical voltage the tube ceases to be condenser Il the period of oscillations established in the grid circuit o! the amplifier seccordingly, to vary the period of impacts upon plate 24 it is merely necessary to vary the resistance 2l.

As an example of the constants employed the illter condensers I3 each comprised condensers of l microfarads. The resistance I4 comprised 2200 ohms. Resistance 34 comprised 1/2 megohm. `Variable resistance 36 comprised 10 megohms. Condenser 2| hada capacity of 1% microtarads and condenser ll had a capacity of tim microfarads.

It is to be understood.of course, that my invention is not to be limited to the use of these particular constants since the same may be varied depending upon the impact frequency desired, the nature of the electron tubes employed and the like.

I claim as my invention: I

l. A device of the class described comprising a plate for supporting a sample of discrete material capable of changing its bulk density when vibrated, electro-magnetic means for vibrating said plate to vibrate said sample, and means for controlling the frequency of vibration of said electro-magnetic means comprising an electron tube, means for setting up oscillations of predetermined frequency in the grid circuit of said electron tube, and relay switch means in the plate circuit of said electron tube connected to said electro-magnetic means to electrically energize said electro-magnetic means in response to the oscillations set up in the grid circuit of said electron tube. a

2. A device of the class described comprising a plate for supporting a sample of discrete material capable of changing its bulk density when vibrated, electro-magnetic means for vibrating said plate to vibrate said sample,and means for controlling the frequency of vibration of said electro-magnetic means comprising an electron, tube, meansl for setting up oscillations of predetermined frequency in the grid circuit of said electron tube, means for controlling the frequency of oscillations in said grid circuit, and relay switch means in the plate circuit of said electron tube connected to said electro-magnetic means to electrically'energize said electro-magnetic means in response to the oscillations set up in the grid circuit of said electron tube.

3. A device of the class described comprising a plate for supporting a sample of discrete mate- `rial capable of changing its bulk density when vibrated, electro-magnetic means for vibrating said plate to vibrate'said sample, and means for controlling the frequency of vibration of said electro-magnetic means comprising an electron tube, means 'for setting up oscillations of predetermined frequency in the grid circuit of said electron tube, said means comprising a glow tube and a condenser connected in parallel, means for establishing voltage across said parallel circuit to charge said condenser, said condenser periodically discharging through said glow tube to set up an oscillating current in said parallel circuit, and means connecting said parallel circuit to the grid of saidelectron tube to vary the potential upon said grid in response to oscillations in said parallel circuit, and relay switch means in the plate circuit of said electron tube connected to said electro-magnetic means to electrically ener- '76 gize said electromagnetic means in response to the oscillations set up in the grid circuit of said denser connected in parallel, means for establishing voltage across said parallel circuitto charge said condenser, said condenser periodically discharging through said glow tube `to set up an oscillating current in said parallel circuit, and means connecting said parallel circuit to the grid \of said electron tube to vary the potential upon said grid in response to oscillations in said parallel circuit, relay switch means in the plate circuit of said electron tube connected to said elec tro-magnetic means to electrically energize said electro-magnetic means in response to the oscillations, set up in the grid circuit of said electron tube, and means for varying the voltage applied to said parallel-circuit to change the frequency of oscillation of said parallel circuit.

5. A device of the class described comprising an impact plate for supporting a sample of discrete material capable of changing its bulk density when vibrated, electro-magnetic means comprising an iron core periodically movable into contact with said plate for vibrating said plate to vibrate said sample, and means for controlling the frequency of vibration of said electro-magnetic means comprising an electron tube having a cathode, plate and grid, means for setting up oscillations of predetermined frequency in the grid circuit of said electron tube, and relay switch means in the plate circuit of said electron tube connected to said electro-magnetic means to electrically energize said electro-magnetic means in response to the oscillations set up in the grid circuit of said electron tube.

6. A device of the class described comprising a plate, a calibrated container carried upon said plate for carrying a sample of discrete material capable vof changing its bulk density when vibrated, electro`-magnetic means for vibrating said pate to vibrate said container` and sample, and

means for controlling the frequency of vibration of said electro-magnetic Vmeans comprising an electron tube, means for setting up oscillations of predetermined frequency in the grid circuit of said electron tube, and relay switch means in the plate circuit of said electron tube connected to said electro-magnetic means to energize said electro-magnetic means in response to the oscillations set up in the grid circuit of said electron tube.

' LE ROY W. LIESCH.

REFERENCES CITED The following references are of lrecord in the file of this patent:

UNITED STATES PATENTS 

